1. Field of the Invention
The present invention relates to a die apparatus, a blanking or stamping speed of which is improved for the purpose of a miniaturization and a manufacturing method of a metal product using the die apparatus.
2. Description of the Related Art
A laminated iron core (one example of a metal product) which forms respectively a rotor or a stator of an electric motor is manufactured in such a way that a thin electromagnetic steel plate (one example of a thin metal sheet) is blanked or stamped out to a prescribed configuration by using a press line (a die apparatus having a plurality of working stations which progressively feed the thin electromagnetic steel plate at prescribed feed pitches and sequentially blank or stamp out the thin electromagnetic steel plate), and a prescribed number of iron core pieces thus formed are laminated and fastened and connected together by a method of caulking or welding.
Here, since the iron core piece is formed in such a way that an inner configuration is blanked or stamped out (a blanking work of an inner peripheral side) and then, an outer configuration is blanked or stamped out, as shown in FIGS. 4A and 4B, the feed pitch P of the thin electromagnetic steel plate is set to an outside diameter of the iron core piece. Further, an idle process (a process that the blanking work is not carried out) is provided between an inner configuration blanking process and an outer configuration blanking process to separate a position where an inner configuration blanking die 81 is press fitted from a position where an outer configuration blanking die 82 is press fitted in a die plate 80. Thus, the die plate 80 which holds the inner configuration blanking die 81 and the outer configuration blanking die 82 integrally is allowed to have a rigidity (a strength) so that the die plate 80 is prevented from being deformed to deteriorate a holding power by the press fitted inner and outer configuration blanking dies 81 and 82 (for instance, see JP-B-6-22375, JP-A-6-276712 and JP-A-11-164527 as Patent Literatures 1 to 3).
Patent Literature 1: JP-B-6-22375
Patent Literature 2: JP-A-6-276712
Patent Literature 3: JP-A-11-164527